Question

a point mutation changes the dna sequence cga to cgt, but the same protein is still produced. which point mutation occurred?

nonsense
missense
silent
frameshift

Explanation:

• Nonsense mutation: Changes a codon to a stop codon, prematurely terminating protein synthesis. But here protein is produced, so not this.
• Missense mutation: Changes a codon to code for a different amino acid. But since same protein is produced, not this.
• Silent mutation: Alters the DNA sequence (here CGA to CGT) but due to the degeneracy of the genetic code (multiple codons can code for the same amino acid), the same protein (same amino acid sequence) is produced.
• Frameshift mutation: Caused by insertions or deletions (not substitutions like here) and disrupts the reading frame, changing the entire amino - acid sequence downstream. Not applicable here as it's a substitution (point mutation) and same protein is made.

Answer:

C. silent